Conventionally, a device for detecting deformation such as a crackle of a structure such as a bridge, a tunnel and the like in a non-contact manner is known (for example, see Japanese Unexamined Patent Application Publication No. Hei 8-248006). The device disclosed in Japanese Unexamined Patent Application Publication No. Hei 8-248006 irradiates a measurement point of an object with an ultrasonic wave and irradiates the measurement point with laser light, and measures a vibration state of the measurement point such as a resonance frequency, amplitude characteristics and attenuation characteristics. The device detects the deformation on the basis of the vibration state of the measurement point.